Introducing POMME Potsdam Magnetic Model of the Earth

• Star camera calibration• Ring current field• Static and annually varying external fields• Internal field

Stefan Maussmaus@gfz-potsdam.de

Stefan Maus, George Balasis,

Hermann Lühr and Martin Rother, GFZ

Mioara Mandea, IPGP

POMME main field model

Internal field:

• Gauss coefficients gnm

to degree 15 tgn

m to degree 15

ttgnm to degree 10

External field:• Dst dependent external

dipole aligned with internal field dipole

• Gauss coefficients knm to

degree 2 in Geocentric Solar Magnetic (GSM) coordinatesStar camera angle:

• corrections for 6 time intervals

Oersted data before/after median filter

Residuals against initial field model

Calibration for the angle between the star sensor and the vector magnetometer

Fluxgate vector magnetometer

Starsensor

Z residuals against Pomme 1.4

Dst dependence of earlier field models

Dst dependence of Pomme

Dst versus induced RC field of Pomme

Magneto-sphere

A constant external field in GSM: Annual variation seen by an Earth fixed observer at

0 degree longitude, 30 degree latitude

A constant external field in GSM: Comparison with CO2’s external field

(observer at 0 degree longitude, 30 degree latitude)

Main field model power spectrum

Model with 3rd time derivative

Conclusions

Stefan Maussmaus@gfz-potsdam.de

Data errors: Important to take instrument errors, star camera mis-alignment and F-Region currents into account

New features in POMME: • Includes co-estimated star camera angles for CHAMP• Imposed realistic Dst dependence of RC field• Describes magnetospheric fields in GSM coordinates• Includes secular acceleration

See: www.gfz-potsdam.de/pb2/pb23/SatMag/model.html

Examples of Instrument Problems

Examples of genuine magnetic disturbances

Diamagnetic effect at 20:00 local time

Night sideF region currents

E - Region

B

Regions of enhanced plasma density

E - Region

B

Regions of enhanced plasma density

E - Region

B

Regions of enhanced plasma density

CHAMP electron density, 23-23 Oct 2001, 20 LT

Diamagnetic effect at 20:00 local time

Satellites POGO (1967-1971)

MAGSAT (1979-1980)– 350 – 650 km altitude– mission duration: 6 months

Oersted (since 1999)SAC-C (since 2001)

– 600 – 800 km altitude

CHAMP (since 2000) – 450 km altitude, decending– 5 year mission